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Finding the Fourth Proportional to 856.78, 1,285.15 and 491.30

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Solution

The fourth proportional to 856.78, 1,285.15 and 491.30 is: 736.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.78 : 1,285.15 = 491.30 : x
  2. Step 2: Convert to fraction form
    856.78/1,285.15 = 491.30/x
  3. Step 3: Cross multiply
    856.78x = 1,285.15 × 491.30
  4. Step 4: Simplify right side
    856.78x = 631,394.20
  5. Step 5: Solve for x
    x = 631,394.20/856.78
  6. Step 6: Final answer
    x = 736.94

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.